1. Field of the Invention
This invention relates to a method, apparatus and article enabling quickly and more easily cutting, breaking and installing building sheets, and more particularly, to building sheets having a surface groove system to guide a cutter without the need for a straight edge.
2. Description of the Related Art
Building sheets made of fiber cement and other materials are often used as backerboards for floors, countertops, walls, etc. For instance, backerboards for ceramic tiles are used for countertops to provide the water resistant, relatively rigid, dimensionally-stable foundation over which the tile is bonded during the installation. Conventionally, the backerboard is laid over an exterior grade sheet of plywood ½ to 1 inch thick and adhered thereto using an adhesive such as a dry-set portland cement mortar or latex-modified portland cement mortar thinset. The backerboard is also fastened to the plywood subfloor using nails or screws. Once the backerboard is in place, ceramic tile is laid over the backerboard and adhered thereto using a modified thinset or other suitable tile adhesives. Backerboards are installed in a similar manner for a number of other applications, such as tile backer for floor installations and wallboard installations where the material is installed direct to stud or exterior sheathing or paneling applications.
For these and other applications, building sheets must generally be sized and cut to an appropriate dimension for installation. For instance, tile backerboards must be appropriately sized and cut before placement over plywood subfloor. This can be a time consuming and labor-intensive process, requiring a number of different tools and great precision to size and cut a board to the desired dimension. Cutting of a backerboard typically requires using a straight edge and scoring knife to score the backerboard on one side, and then snapping the backerboard up against the edge of the straight edge to break the board along the score mark. It is often difficult (particularly for long cuts) to hold the straight edge in a fixed relationship to the material with one hand, and perform the scoring or cutting with the other hand. Resultant slippage can reduce the accuracy of the resulting cut. Alternatively, a circular saw with a carbide tipped blade or shears have also been used to cut backerboards.
To assist in determining a desired cut location, backerboards have been known to contain marker locations, for example markers 6 inches apart marked in ink, to indicate fastening locations for nails or drills. These markers can also provide a visual aid to enable a cutter to more easily locate a desired cutting location. U.S. Pat. No. 5,673,489 to Robell describes a gridded measurement system for construction materials such as wallboards wherein a plurality of horizontal and vertical unit measurement markings are positioned around the perimeter of the construction material surface to provide quick dimensional reference for sizing of the construction material. The construction material surface is filled with horizontal and vertical grid markings between the numbered unit measurement markings.
Construction boards with markings as described above, though generally assisting in visualizing cut locations, still do not significantly decrease the time and labor for installation. This is due in part to the fact that boards with markings still require the use of a straight edge or other tool to guide a cut mark across the board.
Accordingly, what is needed is a method and apparatus for reducing the time and improving the efficiency of installing building sheets such as backerboards, and more particularly, a building sheet that accomplishes some or all of these and other needs.